DESCRIPTION (Applicant's Description): This program is designed to establish the applicant as an independent investigator of biomarker research in bronchial carcinogenesis, and in early detection and chemoprevention of cancers of the upper aerodigestive tract. The applicant has previous research experience in molecular and cellular pharmacology and has recently become an established medical oncologist specializing in the treatment of lung cancer. The sponsor is an accomplished pulmonary physiologist and molecular biologist in the field of development and differentiation of bronchial epithelium, and in the area of regulation of biomarkers of the bronchial epithelium in response to environmental toxins such as ozone and tobacco smoke. The plans of the sponsor are to provide supervision to the applicant to acquire expertise in molecular techniques, in the design and execution of experiments to elucidate the mechanisms of regulation of a molecular marker, spr1, associated with bronchial metaplasia, and in the application of this biomarker for early detection of lung cancer. The sponsor has cloned a small proline-rich protein (spr-1) which is overexpressed in tracheobronchial epithelium undergoing metaplastic change from a normal mucociliary phenotype to a squamous appearance. The spr1 expression is down-regulated by vitamin A and up-regulated by tumor promoters. Therefore, it appears that spr1 is a potential early biomarker for preneoplastic transformation of the bronchial epithelium. In their laboratory, there is a series of human bronchial epithelial cells displaying varied degree of spr1 expression and tumorigenicity potential. This proposal is, thus, intended to use this cell-culture model to elucidate the mechanism of regulation of spr1 expression in the multistep carcinogenesis of the bronchial epithelium, and to use archival specimens to map spr1 expression in the field of cancerization of lung tissues from patients with lung cancer. The first aim is to test the hypothesis that there is an increasing expression of spr1 in the field of cancerization extending from a focus of bronchial squamous carcinoma to the surrounding dysplastic, metaplastic and normal bronchial epithelia as determined by immunohistochemical staining and in situ hybridization of archival human squamous lung carcinoma. The second aim is to use a human tracheobronchial cell model to test the hypothesis that the cell type-specific expression of spr1 is regulated at the level of transcription by using a nuclear run-on transcriptional assay and a transfection study with chimeric constructs of the spr1 promoter region attached to a reporter gene. The third aim is to identify the cis-elements and the transcriptional factors involved in the regulation of spr1 gene by employing the techniques of DNA-binding mobility shift gel assay, DNA footprinting and expression cloning. These studies are to set the stage for using spr1 as a biomarker for identifying the early steps of multistep carcinogenesis, for early detection of lung cancer, and for testing the efficacy and mechanisms of chemopreventive agents in reversing malignant transformation of the bronchial epithelium.